Header structure for heat transfer apparatus

ABSTRACT

An improved header construction for a heat transfer apparatus is provided. The header includes a plurality of connected longitudinally stepped concentric annular rings each adapted to be coupled to the base of a hollow frustoconical member. The top end of each of the frustoconical members is secured to one tube of a plurality of concentric tubes proximal an end of that tube. A method of assembling a heat transfer apparatus utilizing an improved header in accordance with the above is also provided.

United States Patent Cannon [451 Mar. 28, 1972 3,386,497 6/1968 Feldmeier l 65/141 Primary Examiner.lohn F. Campbell [72] Inventor: llsobeki't B. NC;l'lll1(l)l';,6 840 Woodhull PL, Assistant Examiner nonald P. Rooney port Attorneyl(ane, Dalsimer, Kane, Sullivan and Kurucz 22 Filed: Feb. 26, 1970 57 ABSTRACT [21] Appl. No.: 14,576 1 An improved header construction for a heat transfer apparatus is provided. The header includes a plurality of congf 5" g nected longitudinally stepped concentric annular rings each g i M14119?! 5 R 3 C adapted to be coupled to the base of a hollow frustoconical l e 0 ll 3 member. The top end of each of the frustoc'onical members is secured to one tube of a plurality of concentric tubes proximal 56] References Cited an end of that tube. A method of assembling a heat transfer apparatus utilizing an improved header in accordance with the UNITED STATES PATENTS above is also provlded.

3,323,585 6/1967 Cannon 165/14! 3 Claims, 8 Drawing Figures Patented March 28,- 1972 I 4 sheets-sheet 1 FIG. 2

INVENTOR v ROBERT B. CANNON Patented March 28, 1972 3,651,551

4 Sheets-Sheet 2 INVENTOR ROBERT B. CANNON ATTORNEYS BACKGROUND OF THE INVENTION In my recently issued US. Pat. No. 3,323,585 I disclose a header structure for use with a multiple tube heattransfer or heat exchanger apparatus. Although the patented structure produces satisfactory results in a wide variety of applications, certain difficulties have been experienced in installations wherein sanitary conditions are to prevail. These difficulties arise, in particular, due to the-factthat the patented structure does not lend itself to cleaning and inspection of the inlet fittings.

Thus, it is the principle object of the present invention to provide an improved header construction for use with a multiple tube heat transfer device which may readily be removed to provide access to the interior of the associated tubes.

A further object is to provide a simplified method to assemble a heat transfer device utilizing such a header.

SUMMARY OF THE INVENTION The above and other beneficial objects and advantages are attained in accordance with the present invention by providing a heat transfer apparatus comprising a plurality of radially spaced apart concentrically mounted elongated tubular elements including an innermost element, an outermost element and at least one intermediate element. One end of the intermediate element projects beyond the corresponding end of the outer element and the corresponding end of the inner element projects beyond that end of the intermediate element. An equal plurality of hollow frustoconical members is also provided. Each of the members has a base terminating in a plane substantially perpendicular to the longitudinal axis of the tubular elements and a top end coupled to the aforedescribed ends of the tubular elements. A header formed of a plurality of connected longitudinally stepped annular rings is also provided with each of the rings being removably coupled to the base of one of the frustoconical members thereby sealing the passageways defined by the inner and outer surfaces of adjacent tubular members. Means are provided connected to the header for supplying fluids into the passageways and for simultaneously imparting a tangential motion component to the fluid with respect to the tubular elements.

A method of assembling a heat transfer apparatus in accordance with the present invention is also provided wherein the apparatus is formed by joining the ends of several sections of concentrically mounted heat transfer tubes. The tubes comprising each section are uniformly stepped in the longitudinal direction with the innermost tube extended at one end and the outermost tube extended at the other end.Frustoconical connectors are affixed to one end of the tubes of a first section and the other end of the tubes of the first section are connected to the tubes of another section of tubing. The opposed ends of additional sections of tubing are then alternately connected to the apparatus until the desired overall tubing length is attained to provide the desired heat transfer characteristics and then frustoconical connectors are affixed to the free end of the apparatus. Header structures of the type previously described are then connected to each set of frustoconical connectors to complete the assembly.

BRIEF DESCRIPTION OF THEDRAWINGS In the accompanying drawings;

FIG. 1 is a top plan view of a heat transfer apparatus provided with a header structure in accordance with the present invention whereinthe heat transfer tubes comprise a plurality of coil sections formed of curved end pieces and straight center pieces;

FIG. 2 is a side elevational view of the heat transfer apparatus of FIG. 1;

FIG. 3 is a top plan view of a non-coiled heat transfer apparatus provided with the header structure of the present invention;

FIG. 4 is an end view of the header structure of the present invention taken along reference lines 4--4 of FIG. 1 in the direction indicated by the arrows;

FIG. 5 is a side elevational sectional view taken along reference lines 5-5 of FIG. 4 in the direction indicated by the arrows;

FIG. 6 is an exploded view of the header structure of FIG. 5;

FIG. 7 is a fragmentary side elevational view partially in sections of the tubes of the heat exchanger illustrating the tube spacer and turbulence generator embossed thereon; and,

FIG. 8 is a simplified top plan view similar to FIG. 1 illustrating the method of assembling a heat exchanger in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Reference is now made to the drawings and to FIGS. 1 and 2, in particular, wherein one embodiment of a heat transfer apparatus 10 in accordance with the present invention is illustrated. The transfer apparatus 10 includes a helically wound coil portion 12 formed of straight center sections 14 and curved end sections 16. An inlet connector assembly 18 and an outlet connector assembly 20 of identical construction are connected to the substantially straight tubular portions 24 and 26 at the opposed ends of the coil. The heat transfer apparatus 10 of FIGS. 1 and 2 enables a relatively long section of heat transferring surface to be compacted into a relatively short area by virtue of the expedient of coiling the transfer fluid tubes. Occasionallyit is desirable to have the transfer fluid tubes extended or to take on a particular configuration as in FIG. 3. In such cases the ends of the tube are also provided with identical inlet and outlet assembly connectors 18 and20, respectively. As can be seen in FIG. 3, curved sections 28 are used to connect straight sections 14 to obtain the desired configuration. Similarly, curved sections 28 could describe any other desired arc, i.e., 30, 45, 60, etc., to obtain the required curvature.

Referring now to FIGS. 5 through 8, it is noted that the heat transfer tube of the proposed apparatus is formed of three concentric tubes that are made of a suitable, thin walled, light gauged metal preferably a corrosion resisting metal such as stainless steel. In one preferred practice of the invention the innermost tube 30 had an outside diameter of l 56 inches, the diameter of the intermediate tube 32 was 2 h inches, and the diameter of the outside tube 34 was 3 inches. These tubes cooperate in defining three fluid passages 36, 38 and 40. Passage 36 is bounded by the inner wall of tube 30, passage 38 is bounded by the outer wall of tube 30 and the inner wall of tube 32, and passage 40 is bounded by the outer wall of tube 32 and the inner wall of tube 40. The relative spacing between the tubes is maintained by a plurality of spacers 42 and 44 that are embossed on the outer walls of tube 30 and 32 respectively. The spacerelements comprise elongated substantially helical embossments extending longitudinally about their respective tubes to maintain the spacedapart relationship between adjacent tubes and also to cooperate in generating a tangential flow component to the fluid circulated in the tubes.

As was previously mentioned the fluid connector assemblies 18 and 20 coupled to both ends of the transfer tube are of identical construction and hence only a single connector and its component parts will now be described. Generally speaking the connector assembly comprises a plurality of hollow frustoconical distributor elements (seen best in FIG. 6) connected one each to tubes 30, 32 and 34 and a header adapted to receive each of the distributor elements, to seal the passageways between adjacent tubes, and to define terminal connections for the passageways. Thus, frustoconical distributor element 46 is provided for association with outer tube 34, frustoconical distributor element 48 is provided for association with tube 32 and frustoconical distributor flange element 50 is provided for association with tube 30. Element 46 carries an annular base flange 52 disposed transverse to the longitudinal axis of element 46. A plurality of threaded mounting lugs 54 extend outwardly from flange 52 away from element 46. Similarly, element 48 is provided with base flange 56 and the associated mounting lugs 58 and element is provided with base flange 60 and mounting lugs 62.

A header 64 adapted to receive the mounting lugs 54, 58 and 62 of distributor elements 46, 48 and 50 respectively is also provided. Header 64 comprises an elongated generally cylindrical member stepped in the longitudinal direction. The steps are defined by flat annular rings 66, 68 and 70. Ring 70 is provided with mounting holes 72 aligned with lugs 62 of element 50, ring 68 is provided with holes 74 aligned with lugs 58 of element 48, and ring 66 is provided with holes 76 aligned with lugs 54 of element 46. Rings 66 and 68 are connected by cylindrical wall section 78 the diameter of which is substantially equal to the outside of diameter of ring 68. Rings 68 and 70 are connected by cylindrical wall section 80 the diameter of which is substantially equal to the outside of diameter of annular ring 70. As seen in FIG. 5, the longitudinal dimension of section 78 of header 64 is substantially equal to the longitudinal dimension of the tapered portion of distributor element 48 while the longitudinal dimension of wall section 80 is somewhat greater than the tapered portion of element 50.

Inlet (or outlet) conduits 82 and 84 extend radially outwardly from wall section 78 and 80 respectively. These conduits may be provided with suitable fittings for connection to other equipment such as a pump or reservoir.

The fluid connector assembly is formed by welding the distributor elements to one end of their associated tubes and thereafter connecting the base of each distributor element flange to the corresponding annular ring of the header assembly with suitable nuts fastened to the threaded lugs. Gaskets may be provided between the distributor element flange and annular ring to insure against leakage. The forward end of the innermost tube 30 is provided with a suitable connector 86 for direct connection to or from the fluid supply.

The heat transfer apparatus disclosed is formed utilizing standard tube bending equipment and procedures. Referring to FIG. 8, both the curved and straight sections of tubing are formed of the same stock which in this preferred embodiment comprises l A inches, 2 /2 inches and 3 inches O.D. tubing respectively for the innermost, intermediate and outermost tubes. Referring to FIG. 8, the heat transfer apparatus is assembled by first welding a distributor element to one end of the intermediate and outer tubes and spaced inwardly of one end of the innermost tube of a straight section of tubing 87.

The header 89 is then bolted in place and the pieces are precisely measured and cut so that at the opposite end 88 of the tubing section the innermost tube 90 extends approximately five-eighth inch beyond the end of the intermediate tube 92 which extends approximately five-eighth of an inch beyond the end of the outermost tube 94. The five-eighth inch dimension being chosen because of the radius of the inner tube.

A curved section of the apparatus 96 which comprises bent tubes provided with straight extensions on opposite ends which are inversely stepped by intervals of five-eighth of an inch are then butt welded to the straight sections working outwardly from the innermost tube. Thus, at end 98 of section 96 the end 100 of the intermediate tube extends five-eighth inch beyond the end 102 of the innermost tube and the end 104 of the outermost tube extends five-eighth inch beyond the end of 100 of the intermediate tube. End 102 of the innermost tube of curved section 96 is first butt welded to the exposed end 90 of the innermost tube of the straight section. The intermediate curved tube section is then enveloped over the innermost tube starting from free end 106 and end 100 of the curved section is butt welded to end 92 of the straight section whereafter the same procedure is followed for the outermost curved section.

When end 98 of the curved section 96 is completely welded to straight section 87 the free end 106 of section 96 is in condition to accept a straight section 108 formed of tubes of equal length. It should be apparent that although section 96 is illustrated as comprising a 180 bend it could in fact com rise any desired bend. When the ends 110, 112 and 114 of t e innermost, intermediate and outermost tubes of section 108 are butt welded to the corresponding ends 106 of the curved section 96 (again working outward from the innermost tube) the opposite ends 116, 118 and 120 will be stepped in a manner identical to that of end 88 of section 87. By cutting each of the ends at a slight angle (on the order of less than one-half inch for 10 foot lengths) the coil-like effect of FIG. 1 may be attained so that another curved section identical to section 96 may be butt welded to ends 116, 118 and 120. The process can then be repeated utilizing alternate straight and curved sections until the desired length of the heat transfer apparatus is achieved whereafter distributor elements are welded to the free tube ends and nested to produce a reverse step pattern and another header is bolted in place to complete the apparatus.

Thus, in accordance with the above, .an improved header construction for a heat transfer apparatus is provided along with an improved method of assembling such an apparatus. It should be understood that modifications may be made in the illustrated and described embodiments of my invention without departing from the scope of the invention as set forth in the following claims.

Having thus described my invention, what I claim is:

1. The method of assembling a heat transfer apparatus having a plurality of concentrically mounted heat transfer tubes having straight center sections, curved end sections, and connectors affixed to the free ends of said tubes, said method comprising the steps of:

a. forming tube sections by cutting tube elements so that when concentrically mounted to form a section, the tubes comprising the section are uniformly stepped in the longitudinal direction with the innermost tube most extended at one end and the outermost tube most extended at the other end;

b. affixing connectors to the ends of the tubes of a first section, securing a header to said connectors, and connecting the other end of the tubes of said first section to the opposite end of the tubes of another section of tubing to assemble said apparatus;

c. alternately butt welding the opposed ends of additional sections of tubing to said apparatus; and 1 d. affixing connectors to the free ends of the tubing of the last section and securing a header to said connectors.

2. The invention in accordance with claim 1 wherein alternate straight and curved sections of tubing are affixed to said apparatus by butt welding the innermost tube of a section to be added to the extended free end of the innermost tube of the last previous section added; subsequently sliding the intermediate tube of the section to be added over the innermost tube just connected and butt welding said intermediate tube to the intermediate tube of the last previous section and thereafter sliding the outermost tube of the section to be added over the intermediate tube just connected and butt welding said outermost tube to the outermost tube of the last previous section.

3. The invention in accordance with claim 2 wherein said curved sections define arcs of and further comprising the step of cutting the meeting ends of adjacent sections of tubing at an angle with respect to the longitudinal axis of said sections so that the resultant apparatus will assume a substantially spiral configuration. 

1. The method of assembling a heat transfer apparatus having a plurality of concentrically mounted heat transfer tubes having straight center sections, curved end sections, and connectors affixed to the free ends of said tubes, said method comprising the steps of: a. forming tube sections by cutting tube elements so that when concentrically mounted to form a section, the tubes comprising the section are uniformly stepped in the longitudinal direction with the innermost tube most extended at one end and the outermost tube most extended at the other end; b. affixing connectors to the ends of the tubes of a first section, securing a header to said connectors, and connecting the other end of the tubes of said first section to the opposite end of the tubes of another section of tubing to assemble said apparatus; c. alternately butt welding the opposed ends of additional sections of tubing to said apparatus; and d. affixing connectors to the free ends of the tubing of the last section and securing a header to said connectors.
 2. The invention in accordance with claim 1 wherein alternate straight and curved sections of tubing are affixed to said apparatus by butt welding the innermost tube of a section to be added to the extended free end of the innermost tube of the last previous section added; subsequently sliding the intermediate tube of the section to be added over the innermost tube just connected and butt welding said intermediate tube to the intermediate tube of the last previous section and thereafter sliding the outermost tube of the section to be added over the intermediate tube just connected and butt welding said outermost tube to the outermost tube of the last previous section.
 3. The invention in accordance with claim 2 wherein said curved sections define arcs of 180* and further comprising the step of cutting the meeting ends of adjacent sections of tubing at an angle with respect to the longitudinal axis of said sections so that the resultant apparatus will assume a substantially spiral configuration. 